1. Field of the Invention
The present inventions relate to tools for use in and in conjunction with the assembly, maintenance, management, cleaning and operation of pipelines, which tools utilize high power laser energy. Thus, and in particular, the present inventions relate to novel pipeline tools, such as a laser-pig.
As used herein the term “pipeline” should be given its broadest possible meaning, and includes any structure that contains a channel having a length that is many orders of magnitude greater than its cross-sectional area and which is for, or capable of, transporting a material along at least a portion of the length of the channel. Pipelines may be many miles long and may be many hundreds of miles long. Pipelines may be located below the earth, above the earth, under water, within a structure, or combinations of these and other locations. Pipelines may be made from metal, steel, plastics, ceramics, composite materials, or other materials and compositions know to the pipeline arts and may have external and internal coatings, known to the pipeline arts. In general, pipelines may have internal diameters that range from about 2 to about 60 inches although larger and smaller diameters may be utilized. In general natural gas pipelines may have internal diameters ranging from about 2 to 60 inches and oil pipelines have internal diameters ranging from about 4 to 48 inches. Pipelines may be used to transmit numerous types of materials, in the form of a liquid, gas, fluidized solid, slurry or combinations thereof. Thus, for example pipelines may carry hydrocarbons; chemicals; oil; petroleum products; gasoline; ethanol; biofuels; water; drinking water; irrigation water; cooling water; water for hydroelectric power generation; water, or other fluids for geothermal power generation; natural gas; paints; slurries, such as mineral slurries, coal slurries, pulp slurries; and ore slurries; gases, such as nitrogen and hydrogen; cosmetics; pharmaceuticals; and food products, such as beer.
Pipelines may be, in part, characterized as gathering pipelines, transportation pipelines and distribution pipelines, although these characterizations may be blurred and may not cover all potential types of pipelines. Gathering pipelines are a number of smaller interconnected pipelines that form a network of pipelines for bringing together a number of sources, such as for example bringing together hydrocarbons being produced from a number of wells. Transportation pipelines are what can be considered as a traditional pipeline for moving products over longer distances for example between two cities, two countries, and a production location and a shipping, storage or distribution location. The Alaskan oil pipeline is an example of a transportation pipeline. Distribution pipelines can be small pipelines that are made up of several interconnected pipelines and are used for the distribution to for example an end user, of the material that is being delivered by the pipeline, such as for example the feeder lines used to provide natural gas to individual homes. As used herein the term pipeline includes all of these and other characterizations of pipelines that are known to or used in the pipeline arts.
As used herein the term “pig” is to be given its broadest possible meaning and includes all devices that are known as or referred to in the pipeline arts as a “pig” and would include any device that is inserted into and moved along at least a portion of the length of a pipeline to perform activities such as inspecting, cleaning, measuring, analyzing, maintaining, welding, assembling, or other activities known to the pipeline arts. In general, pigs are devices that may be unitary devices, as simple as a foam or metal ball, or a complex multi-component device such as a magnetic flux leakage pig. In general, pigs are devices that when inserted in the pipeline travel along its length and are moved through the pipeline by the flow of the material within the pipe. Pigs may generally be characterized as utility and in-line inspection pigs, although these characterizations may be blurred and may not cover all potential types of pigs. Utility pigs perform such functions as for example cleaning, separation of products and removal of water. In-line inspection pigs, would include gauge pigs, as well as, more complex pigs, which may also be referred to by those of skill in the art as instrument pigs, intelligent pigs or smart pigs. Smart pigs perform such functions, as for example, supplying information on the condition of the pipeline, as well as, on the extent and location of any problems with the pipeline. Pigs are used both during the construction and during the operational life of the pipelines. Pigs may also be used in the decommissioning of a pipeline and its removal.
As used herein the term “earth” should be given its broadest possible meaning, and includes, the ground, all natural materials, such as rocks, and artificial materials, such as concrete, that are or may be found in the ground, including without limitation rock layer formations, such as, granite, basalt, sandstone, dolomite, sand, salt, limestone, rhyolite, quartzite and shale rock.
As used herein the term “borehole” should be given it broadest possible meaning and includes any opening that is created in the earth, in a structure (e.g., building, protected military installation, nuclear plant, or ship), or in a structure in the ground, (e.g., foundation, roadway, airstrip, cave or subterranean structure) that is substantially longer than it is wide, such as a well, a well bore, a well hole, a micro hole, slimhole and other terms commonly used or known in the arts to define these types of narrow long passages. Although boreholes are generally oriented substantially vertically, they may also be oriented on an angle from vertical, to and including horizontal. Thus, using a vertical line, based upon a level as a reference point, a borehole can have orientations ranging from 0° i.e., vertical, to 90°,i.e., horizontal and greater than 90° e.g., such as a heel and toe. Boreholes may further have segments or sections that have different orientations, they may have straight sections and arcuate sections and combinations thereof; and for example may be of the shapes commonly found when directional drilling is employed. Thus, as used herein unless expressly provided otherwise, the “bottom” of a borehole, the “bottom surface” of the borehole and similar terms refer to the end of the borehole, i.e., that portion of the borehole farthest along the path of the borehole from the borehole's opening, the surface of the earth, or the borehole's beginning. A pipeline may be positioned within a borehole. Similarly, a borehole may be used as a pipeline or portion of a pipeline.
As used herein, unless specified otherwise “high power laser energy” means a laser beam having at least about 1 kW (kilowatt) of power. As used herein, unless specified otherwise “great distances” means at least about 500 m (meter). As used herein the term “substantial loss of power,” “substantial power loss” and similar such phrases, mean a loss of power of more than about 3.0 dB/km (decibel/kilometer) for a selected wavelength. As used herein the term “substantial power transmission” means at least about 50% transmittance.
2. Discussion of Related Art
Pigging Activities
In general, pigs may be used in pipeline activities to perform various operations on a pipeline, including inspecting, cleaning and assembling. The pigs may be moved through the pipeline by the force of a material that is being pumped or otherwise moved through the pipeline. Pigging operations, i.e., the use of a pig, can be done without stopping the flow of the product in the pipeline, by substituting the flow of the product with the flow of another fluid, such as nitrogen to move the pig through the pipeline, or by having no flow of material through the pipeline and having the pig have an independent motive means for movement through the pipeline.
In general, pigging is accomplished by inserting the pig into a pig launcher or launching station, which may generally be a valved off-shoot section of the pipeline that enables the pig to be placed into the launcher, sealed, and then have the flow of the pipeline material move the pig from the launcher into the pipeline itself. The pig is removed from the pipeline at a pig catcher or receiving station that in most embodiments is similarly, in general, a valved off-shoot to enable removal of the pig from the pipeline.
In general, pigs require a mechanism or structure to drive them through, or along, the interior of the pipeline. Such devices are well known to the pipeline arts and would include things ranging from a simple sphere or ball, that by its own shape and size is pushed through the pipeline by the force of the pipeline fluid to the use of a drive cup and combinations of drive cups, which are sections of the pig that are specifically designed to catch the flow of the fluid in the pipeline and be driven forward by that force of that fluid flow. For example, scraper pigs, brush pigs, and more complex pigs may typically have a cup or set of cups at the front of the pig that are pushed by the material moving through the pipeline. These cups in turn pull the rest of the pig through the pipeline. Thus, differential pressure acting between the front and back of the drive cups provides a force along the pipe axis. This force propels the drive cups, which in turn pulls the rest of the pig.
The driving force from the cups, in general, should overcome the friction between the pig and the internal surfaces of the pipeline. The pressure differential required to move for example a 24-inch pig may be between about 6.9 psi and 10.4 psi. Although, greater pressure differentials may in general be needed to start a non-moving pig, push a pig through an uphill section of pipeline or a dislodge pig that has become stuck. These pressure differentials, to move the pig, are relatively small compared to the typical pipeline pressure during in-line inspection of about 300 to 600 psi. Operation pressures in some lines may be as great as 800 to 1,000 psi, however, greater and smaller pressures may also be seen in various pipeline operations. In general, drive cups are typically at the front of the pig. Additional cups can be used to center portions of a pig in the pipeline. To prevent fluid pressure from pushing a trailing portion of a pig into a leading portion, the fluid can be vented through holes in trailing cups or through a bypass on the pig components. Wheeled assemblies may also be employed to provide centering support for trailing pig portions. Multiple drive cups may be use to assist the pig in moving past pipeline connections. At tee connections and at valves, the differential pressure across a cup can drop if gas bypasses around the cup. Thus, an additional set of drive cups may overcome this loss of motive pressure, by spacing the cups far enough apart so that one cup is always away from the area of the connection or valve.
Pipeline Corrosion and Damage
In general, one of the important roles for pigs and pigging operations is to detect damage to pipelines before that damage can cause a failure of the pipeline and a potentially serious pipeline accident. Pipeline accidents and failures can be caused by many sources, including for example: external damage from excavators and nature; material deficiencies; stress cracking; weld, grout or joint deficiencies; corrosion; and combinations of these and other events.
Corrosion has been related to several recent natural gas transmission pipelines accidents and, by some estimates, corrosion damage and abatement costs the pipeline industry more than $5 billion annually. A major cause of corrosion and of corrosion related failures in pipelines is microbiologically influenced corrosion (“MIC”) MIC occurs when bacteria, or other microbes, grow on the inner surface of a pipeline. In general, sulphate reducing bacteria (“SRB”) are one of the major types of bacteria that cause MIC. These bacteria release byproducts that break down the metal that forms the pipeline walls, and in particular carbon steel pipelines. By some estimates as much as $1.5 billion annually is spent on chemicals to inhibit the growth of such bacteria. It was reported in a 2009 Current Science Article (B. Anandkumar, Effect of thermophilic sulphate-reducing bacteria (Desulfotomaculum geothermicum) isolated from Indian petroleum refinery on the corrosion of mild steel, p. 142 (Current Science, Vol. 97, No. 3, Aug. 10, 2009)) that SRBs have been estimated to have been responsible for over 75% of corrosion in oil wells, and for over 50% of the failures in buried pipelines and cables.
Typically, such bacterial growth is found in the form of a biofilm. These biofilms may be very complex and are formed when the colonizing bacteria, or other microbes, become encapsulated in a slimy, exopolymeric substances composed for example from secreted compounds, such as polysaccharides, proteins, and nucleic acids. These biofilms may have a high level of adherence to the inner surface of the pipeline and may further protect the underlying microbes from biocides, or other treatment chemicals, that are flowed through the pipeline.